But it said under Labor, which has vowed to restore the reduction in penalty rates, much of that money would be pumped straight back into the economy, as those earning Sunday penalty rates are likely to spend the money locally.

Under the cuts to penalty rates, hospitality workers would be $837 million worse off, retail workers would receive $1.64 billion less, and pharmacy workers would be $85 million out of pocket.

McKell Institute Victoria executive director James Pawluk said business lobby groups pushing for lower penalty rates to be retained argue that it stimulates employment.

"Yet there is no compelling evidence to suggest that lowering penalty rates has affected employment in the affected sector," he said in a statement on Saturday.

Instead, the primary effect of retaining lower penalty rates transfers billion of dollars from retail and hospitality workers to business owners and shareholders.

"There does not seem to be an economic or ethical justification for such a transfer at this time," Mr Pawluk said.

Labor's employment spokesman Brendan O'Connor seized on the report, saying penalty rates are not a luxury, but help people put food on the table and petrol in the car.

"Just imagine how much further these cuts could spread if the Liberals are re-elected," Mr O'Connor said in a statement.

Labor has promised to legislate to reverse the cuts to penalty rates in its first 100 days of government should it win the May 18 election.

Australian Associated Press